Truncus Arteriosus - An Overview

Introduction

Truncus arteriosus is an uncommon congenital heart defect that occurs during the development of the fetus. The condition poses significant challenges and requires immediate diagnosis and treatment. This article briefly explains truncus arteriosus, its symptoms, diagnosis, complications, treatment, and outlook.

What Is Truncus Arteriosus?

Truncus arteriosus is a congenital (present at birth) heart defect. During the fetus's development, when the heart is forming, there is a single large blood vessel coming from the heart called the truncus arteriosus. As fetus development progresses, the truncus arteriosus divides into two arteries that carry blood out of the heart:

• The pulmonary artery; artery is attached to the right lower chamber called the ventricle of the heart. The artery is further divided into two arteries carrying oxygen-poor blood to each side of the lungs.

• The aorta: this artery is attached to the left lower chamber (ventricle) of the heart. It carries oxygen-rich blood to the rest of the body.

Occasionally, during fetal development, the single major blood vessel fails to split, resulting in a baby's heart having only one artery pumping blood out of it at birth. This congenital heart defect is known as truncus arteriosus or persistent truncus arteriosus. Truncus arteriosus is regarded as a critical congenital heart defect (CCHD) as a newborn with this abnormality may require surgery or other operations shortly after birth. Children with truncus arteriosus often have a huge hole between the lower chambers of their hearts, which is referred to as a VSD (ventricular septal defect).

In babies with a truncus arteriosus, blood from the bottom chambers (the right and left ventricles) is expelled into the undivided artery-truncus arteriosus, the oxygen-poor blood from the bottom chamber of the right ventricle and the oxygen-rich blood from the bottom chamber of the left ventricle mixes up. Some portion of this mixed blood travels to the lungs, and some goes to the rest of the body. Often, too much blood returns to the lungs than average. This makes breathing more difficult for babies.

What Is the Incidence Rate Of Truncus Arteriosus?

In liveborn neonates, truncus arteriosus (TA) accounts for 1 to 2 percent of congenital cardiac abnormalities. It makes up 4 percent of critical congenital heart defects. The incidence of TA is seven cases per 100,000 live births annually.

What Are the Symptoms of Truncus Arteriosus?

Symptoms of Truncus Arteriosus include:

• Bluish skin (cyanosis).

• Delayed growth or growth failure.

• Fatigue.

• Lethargy.

• Poor feeding.

• Rapid breathing (tachypnea).

• Shortness of breath (dyspnea).

• Widening of the fingertips (clubbing).

How Is Truncus Arteriosus Diagnosed?

Truncus arteriosus can be diagnosed during pregnancy or shortly after the baby's birth. Diagnosis involves the combination of physical examinations and other tests:

• Physical Examination: Shortly after birth, the doctor will look for signs and symptoms of truncus arteriosus, such as bluish skin (cyanosis), rapid breathing, heart murmur, weak pulse, or poor feeding.

• Electrocardiogram (ECG): This test measures the electrical activity of the heart to detect any abnormal heart rhythm.

• Echocardiogram (Also Called "Echo" or Ultrasound): This test creates a detailed image of the heart.by using sound waves.

• Chest X-ray: A chest X-ray may show an enlarged heart and lungs, which occurs due to abnormal blood flow.

• Cardiac Magnetic Resonance Imaging (MRI): It provides a three-dimensional image that shows the heart's abnormalities.

• Cardiac Catheterization: A thin tube called a catheter is inserted into the heart through a blood vessel to obtain diagnostic information about the heart and its vessels.

• Angiography: It is a type of X-ray used to check blood vessels with a special dye injected into the blood.

• Genetic Testing: Genetic testing should be performed for all patients born with truncus arteriosus due to the prevalent association with 22q11 genetic mutations, also known as DiGeorge syndrome.

What Are the Possible Complications of Truncus Arteriosus?

Possible complications of Truncus Arteriosus include:

• Heart Failure: In truncus arteriosus, there is an abnormal blood flow. To compensate for irregular blood flow in the heart. The heart works hard, and as a result, the heart gradually weakens and becomes less efficient at pumping blood, which eventually leads to heart failure.

• Pulmonary Hypertension (High Blood Pressure in the Lungs): In truncus arteriosus, more than normal blood flows to the lungs; the blood vessels to the lungs become permanently damaged if the conditions are left untreated, and with time, it becomes very hard for the heart to pump blood through them. This condition is known as pulmonary hypertension, and it may be fatal.

What Is the Treatment of Truncus Arteriosus?

Treatment of truncus arteriosus involves the following:

1. Medications: Some babies with truncus arteriosus will also require medication to reduce blood pressure, strengthen the heart muscle, and aid in the elimination of the extra body fluid.

2. Nutrition: Some infants with truncus arteriosus may experience fatigue during feedings and may not consume enough food to put on weight. Babies may be administered a special high-calorie formula to ensure a healthy weight increase. Some newborns may require feeding tubes because they get quite exhausted throughout the feeding process.

3. Surgery: Surgery is usually done after a few months after the baby is born. The goal of the surgery is to repair truncus arteriosus.To repair this defect surgery involves the following steps:

• Repairing ventricular septal defect (the hole between the lower chambers of the heart) usually with a patch.

• Creating a new aorta from the original single blood vessel to carry oxygen-rich blood from the left ventricle out to the body.

• Separating the pulmonary arteries from the original single blood vessel, and then connecting the pulmonary arteries to the right lower chamber (ventricle) of the heart using different kinds of conduits (tubes).

What Is the Outlook (Prognosis) of the Patient With Truncus Arteriosus After Surgical Repair?

Good outcomes are typically obtained from complete repairs. An additional procedure is necessary as the child grows because the reconstructed pulmonary artery that uses tissue from a different source will not grow with the child. If left untreated, truncus arteriosus results in death, usually during the first year of life.

Conclusion

Truncus arteriosus is a complex congenital heart defect that poses significant challenges to affected individuals and their families. When diagnosed early and with appropriate treatment, the outcome of the condition is good. Patients can live a better quality of life.